Thermoplastic (non-thermoset) epoxy resins have been employed in the formulation of highway pavement marking paints as disclosed by J. M. Dale in Development of Lane Delineation With Improved Durablity, Report No. FHWA-BD-75-70 July 1975, available from U.S. Dept. of Trans. Off. of Dev., Federal Hwy. Adms., Wash. D.C., 20590. The paint formulations are maintained at elevated temperatures, usually 450.degree. F. to 500.degree. F., during application. While they provide an excellent highway marking paint in terms of abrasive resistance, they are deficient in terms of applicability since they exhibit a substantial increase in viscosity while being maintained at the application temperature. Even if the thermoplastic epoxy resins could maintain its viscosity, the resulting thermoplastic epoxy resins do not have the necessary flexibility to allow wide-spread use.
It would be desirable to have a thermoplastic (non-thermoset) epoxy resin which exhibits a much reduced viscosity increase at elevated temperatures, i.e. it is more thermally stable and exhibits improved flexibility over those thermoplastic epoxy resins disclosed by J. M. Dale. It is desirable that the flexibility of the formulated thermoplastic resin for use in highway marking paints be at least about 15 percent.